1. Field of the Invention
The present invention generally relates to improvements of the structure of a T-joint for connecting a metal branch pipe which has a relatively thin wall thickness of about 1.5 mm or less and a small diameter of about 20 mm or less and is frequently used for automobiles, various kinds of machines, facilities, equipment, and the like, as a branch pipe for supplying oil, air or similar.
2. Description of the Prior Art
Conventionally in this kind of T-joint, as illustrated in FIG. 4, a joint body is arranged as follows: A metal piping material is cut to a short length, and a communicating opening 12 is provided in a substantially central portion of a peripheral wall thereof to form a piping wall 11, which is formed by cutting a metal piping material to a short length and in which a saddle-like curved wall 14 is formed by expanding one end thereof outwardly, is fitted on the piping wall 11 such as to communicate with the communicating opening 12 thereof. Contact surfaces of these members are then fused by means of brazing 15.
P.sub.1 denotes a main pipe which is installed in the piping wall 11 in such a manner as to penetrate the interior thereof and is fused therein by means of brazing W.sub.1 with end peripheries of the pipe 11. P.sub.2 denotes a branch pipe which is connected to the branch piping wall 13 such as to communicated therewith, brazed at W.sub.2 with the end peripheries of the branch piping wall, and includes a round opening B.sub.1 bored in correspondence with the communicating opening 12.
However, in conventional T-joints such as one described above, an operating efficiency is remarkably deteriorated, since for the sake of brazing along the curved wall 14 the communicating opening 12, branch pipe P.sub.2 and round opening M.sub.1 need to be temporalily fitted with each other after positioning them relative to one another, in terms of a brazed structure of different bodies of the cylindrical wall 11 and branch piping wall 13. Also, in a conventional T-joint, there are problems such as a possibility of leak induced by a poor brazing performance using a burner on mutually curved contact surfaces over cylindrical surfaces, a deterioration of mechanical strength of the brazed part caused by a partial overheating, or frequent cracking and bending caused by vibration during arrangement and use of the joint.
Further, productivity is subject to a remarkable deterioration owing to leak, cracking or bending of the joint in the same way as described above because of its structure in which the main pipe P.sub.1 and the branch pipe P.sub.2 are connected to each other by means of brazing at W.sub.1 and W.sub.2.